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Discussion Starter · #1 ·
Looking to tear out existing HVAC ducts in house and redoing for several reasons. Considering DIY of new ducting. Am I nuts?

Long version:
I'm on a roll with home improvements
about to complete my current project (knocking down 2 walls and combining 2 rooms) one of my upcoming projects is to completely redo my basement. Part of this will be moving the HVAC ducts. I may even move the furnace.

Details on existing system and house:
The furnace a 80% efficiency non-condensing Carrier natural gas, but its only 5 years old, so it should have plenty of life. House is 1950's with central heat and air, all sheet metal ducting run in the basement parallel the main beam- however here's my complaints so far:

1) The basement is already low ceilings at 7 feet. The HVAC ducts run down the middle of the basement ceiling and underneath that area is 6' 3"

2) The house has reverse flow venting- as in, in most areas the returns are on the exterior walls (uninsulated! for now) and the supply are on the interior walls

3) There are only 2 (one on the furnace/AC itself) supplies on the basement and ZERO returns
except the furnace itself

4) The grilles are noisy- (when I remove them it's quiet), which brings me to:

5) The ducts are an odd size which I read is common for an older house, like 5x8 so it's almost impossible to find grilles for the vents. Which ties along with this- because of their off size, they are placed low on walls, and not the floors, so I have to use them with this ugly baseboard trim (it goes almost 8" up on the wall).

Sooooo to address these issues, while in the midst of tearing apart my basement since I'll have full access, I plan on:

1) running the Supply and return ducting down one side of the basement wall (without basement windows) instead of the center as you see in most homes. This way, I can build a soffit.

1B) An alternative- would be to run the ducting through the attic (PLENTY of room up there) but that's another ball game needing more ducting and insulation and still needing ducting for the rest of the basement etc.

2 and 3) While I'm at this, I'll change the flow to be "correct" with the supply at the exterior walls and return in the interior walls. Add the proper supplies and returns to the basement.

4) I'll do load calculations, etc make sure the duct sizes are correct.

5) With standard sized ducting, I'd cut new floor vents, which will allow me to use better looking trim throughout the house and use nearly any modern sized vent

The house isn't that big, it's only 1000 sq ft per level. I've never done HVAC stuff before, but I can't imagine working with ducting to be that difficult. Any suggestions?

42,576 Posts
Alright sounds good. Any thoughs on running the main trunk down the side of the basement instead of the center?
Its not a problem, the supply runs to the other side of th house will probably nee to be a little larger, but thats no big deal.
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